A wafer receiving conductive input/output bumps on the upward front side is placed on a platen. An underfill material sheet, adhered to the surface of the thin film tape, is superposed on the front side of the wafer. The underfill material sheet is forced to soften. When the underfill material sheet is urged against the wafer, the input/output bumps is allowed to penetrate through the underfill material sheet. After the underfill material is hardened, the thin film tape is peeled off from the hardened underfill material sheet. The underfill material can thus be supplied commonly to a large number of individual semiconductor chips included in the wafer. As compared with the case where the underfill material is supplied separately to the individual semiconductor chips, the working time can greatly be shortened.